Process for in-line extrusion of coatings onto roofing shingles during manufacturing and roofing shingles made by the process

ABSTRACT

A process for in-line extrusion of polymeric coatings onto roofing shingles during manufacturing includes moving a web of shingle substrate material in a downstream direction and extruding a liquefied coating of polymeric material onto at least one surface of the moving web to form a thin film. The liquefied coating may be a molten polymeric material that forms a thin film on a back surface of the shingle material to prevent sticking and eliminate the need for a traditional back dusting with material such as powdered stone. The polymeric film further may be applied to the substrate material in lieu of a saturation coating of asphalt, thus reducing cost and weight while providing a comparable moisture barrier and a lighter more flexible shingle.

REFERENCE TO RELATED APPLICATIONS

Priority is hereby claimed to the filing date of U.S. provisional patentapplication 62/180,377 filed on Jun. 16, 2015 and to the filing date ofU.S. provisional patent application 62/296,903 filed on Feb. 18, 2016.The content of these provisional patent applications is herebyincorporated by reference.

TECHNICAL FIELD

This disclosure relates generally to the manufacturing of asphaltroofing shingles and more specifically to the application of films orcoatings such as thin films of polymeric material to a web of shinglematerial during the manufacturing process.

BACKGROUND

Asphalt shingles generally are composed of a support layer or substrate,traditionally a felted fibrous layer or a fiberglass or glass mat layer.The support layer is saturated and impregnated with a waterproofingagent, such as a bituminous composition such as a blown moltenpetroleum-based asphalt composition. Excess asphalt is removed byscraping, leaving a waterproof asphalt saturated substrate.Subsequently, the asphalt saturated substrate is coated on one or bothsides and to a predetermined thickness with a molten bituminous coatingthat may contain a finely ground mineral stabilizer or other fillers.This coating is sometimes referred to as a “filled coating.”

While the filled coating is still in a plastic or molten state,ceramic-coated mineral granules, normally opaque to ultraviolet light,are dropped and pressed onto at least the weather exposed portions ofthe filled coating. The granules become embedded in and cover the filledcoating. When exposed to sunlight on a roof, the granules act to protectthe filled coating and the saturated substrate from ultraviolet rays oractinic effects of the sun, as well as providing a decorative aesthetic.Cellophane strips may be applied to be back surface of the web toprevent the self-seal adhesive of stacked shingles from sticking in abundle. A thin layer of powdered mineral matter or fine sand also may beapplied to the back surface in a process known as back dusting. Thestrips and back dusting material prevent individual shingles cut from afinished web from sticking together when stacked in bundles. Traditionalprior art shingle webs can tend to be relatively inflexible duringmanufacturing. This, in turn, can lead to damage during themanufacturing process as webs of shingle material encounter machine linebend radiuses and other stresses along the line.

The application of a polymeric film to the back and/or front surfaces ofan asphalt coated shingle web during manufacturing has previously beensuggested. When applied to the back surface, such film can eliminate theneed for back dusting since the film itself provides the desirednon-stick properties. The film can provide additional advantages such asenhanced adhesion along the glue lines between courses of shingles dueto the more uniform and dust free surface of the film compared to atraditional back dusting material. It may also be advantageous to applyfilms in areas that will become other regions of an asphalt shingle suchas, for instance, in areas that will become the headlap portions ofshingles. Even granule covered portions that will be exposed to theenvironment when shingles are installed may incorporate a polymeric filmto provide greater protection from exposure to the elements as well asmanufacturing efficiencies.

With regard to the application of films to webs of shingle material, theprior art suggests continuously withdrawing a sheet of film from aprefabricated roll and merging the film with a moving web of shinglematerial as the web and the film are conveyed in a downstream processingdirection. However, certain problems are inherent in such a technique.For instance, in order for a film to be rolled onto a prefabricated rollfor use, the film must be strong enough to resist tearing, folding, andother damage during the rolling process and during the process ofapplying the film to a web of shingle material. The thickness of thepolymeric material has to be sufficient to meet these criteria. However,such thicknesses often are significantly greater than is necessary toprovide the desired benefit to shingles. Accordingly, the volume ofpolymeric material and thus manufacturing costs are increased. Also, thesourcing, storage, and manipulation of large rolls of polymeric film addextra complication and cost. Further, just as with rolls of substrate,the rolls of film must be monitored during manufacturing and mechanismsmust be provided to replace rolls as they become empty without having tostop the manufacturing line.

A need exists for a method of applying films and other coatings to amoving web of shingle material during the manufacturing process thataddresses and resolves the above and other problems and shortcomingswith prior art methods. It is to the provision of such a method, and ofshingle products produced by the method, that the present invention isprimarily directed.

SUMMARY

Briefly described, a method is disclosed for applying a thin polymericfilm to a moving web of asphalt shingle material during manufacturing.The method includes extruding the material of the film such as a polymerin a molten or liquid form onto the web as the web moves in a downstreamprocessing direction. The extruded film material is then allowed to cureto form a thin film that is bonded to the web of shingle material. Thematerial may be extruded as a sheet or curtain that drops onto themoving web. Alternatively, it may be applied with a controlled extrusiondie such as a slot die that ejects the liquid film material onto themoving substrate under pressure. The material can be stored efficientlyas pellets that are melted or otherwise liquefied just prior toapplication. Accordingly, the need to source, ship, store, and handlelarge rolls of prefabricated film is eliminated, as is the need toaccommodate replacement of depleted rolls without stopping themanufacturing line.

The film can be applied across the entire width of a web of shinglematerial. This may be desirable when the film is applied to the backsurface of the web as a substitute for a traditional back dusting.Alternatively, the film may be extruded just onto preselected locationsacross the width of a web of shingle material such as, for instance,locations that will become the headlap portions of finished shingles. Itis even envisioned that the extrusion of a polymeric film may substitutefor application of a traditional filled asphalt coating. In eitherevent, the extrusion rate of the liquid film material is metered andcontrolled such that the resulting film applied to the web of shinglematerial is just thick enough to provide a desired advantage but not sothick as to increase cost unnecessarily.

Webs of shingle material incorporating films in place of back dustingmaterial and/or filled asphalt coatings can be significantly moreflexible than webs of traditional shingle material, and thus less proneto damage as the web moves down the manufacturing line. Further,lamination adhesives between the layers of laminated shingles can form asignificantly better bond to the extruded polymeric film because thereis far less loose dust and inconsistency between the layers compared totraditional back dusted shingles.

In an alternative embodiment, a thin film of polymeric material isextruded onto the back surface of a shingle substrate that is notsaturated with an asphalt sealant. The polymer film forms a waterproofbarrier and replaces the traditional asphalt saturation coat. A coatingof filled asphalt may then applied to the upper surface of thesubstrate. Granules dropped onto the hot filled asphalt coating completethe web of shingle material.

It will thus be seen that a novel method is now provided for applyingthin films to moving webs of shingle material during the manufacturingof shingles that addresses successfully the problems and shortcomings ofthe prior art and provides additional novel advantages. These and otheraspects, features, and advantages will become more apparent upon reviewof the detailed description set forth below when taken in conjunctionwith the accompanying drawing figures, which are briefly described asfollows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a greatly simplified schematic illustration of a typical priorart asphalt shingle manufacturing line showing many of the variousprocessing stations along the processing path.

FIG. 2 is a simplified schematic illustration of a method of applyingfilms to a moving web of shingle material according to one exemplaryembodiment of the invention.

FIG. 3 is a lateral cross-section showing one example of a shinglemanufactured according to the method of this invention.

FIG. 4 is a greatly simplified schematic illustration of a method ofmanufacturing shingles with applied polymeric films in lieu of asaturation coating on the shingle substrate.

FIG. 5 is a cross-sectional illustration of a layered shingle materialgenerated by the method illustrated in FIG. 4.

DETAILED DESCRIPTION

The invention will now be illustrated and described in terms ofembodiments that exemplify various modes of carrying out the method ofthe invention. In the description that follows, the word “film” will beused for ease of discussion to refer to material that is applied to amoving web of shingle material. It will be understood, however, that theword “film” as used herein is intended to include and should beconstrued to include a layer of any material that is desired to beapplied to the web. For example, and without limitation, “film” mightinclude a thin layer of polymeric material such as a polyethylene,polypropylene, polyvinyl chloride (PVC), a Nylon, a Polyester, and allpolyolefins. The invention illustrated herein is intended to encompassfilms created from any polymer capable of being extruded into a thinfilm. “Film” might also include a thin layer of an organic material suchas an asphalt composition or a layer of adhesive or any other materialthat is desired to be applied to a web of shingle material during themanufacturing process.

Reference will now be made in more detail to the drawing figures,wherein like reference numerals indicate like components throughout theviews. FIG. 1 is a simplified schematic illustrating a typical prior artasphalt shingle manufacturing process. The process is well understood bythose of skill in the art, and so need not be described in great detailhere. However, it is believed to provide useful background for thediscussion that follows. Briefly, an asphalt shingle manufacturing line11 includes a substrate supply station 12 at the upstream end of themanufacturing line. The substrate, usually in the form of a non-wovenglass mat or fiberglass web, is drawn from a large roll across asplicing table 13 to accommodate splicing of two webs together whenrolls must be changed out. The web is wide enough to accommodate thecutting of multiple shingles from its width at the end of the process.An accumulator or dry looper 14 accumulates a sufficient length of thesubstrate web so that manufacturing can continue as rolls of substratematerial are changed.

The substrate web next is conveyed through a coating station 16, whichmay include a saturator that saturates the web with molten asphalt tocreate a waterproof barrier and a coater that applies a metered layer offilled asphalt to the saturated web. The web then passes beneath agranule application station 17. Here, protective ceramic-coated claygranules are dropped or otherwise delivered onto the hot molten filledasphalt coating, at least in regions that will become exposed areas ofshingles, to form a UV protective coating. Loose granules that do notstick to the asphalt are recovered with the use, for example, of a claydrum (not shown). A back dusting station 18 applies backing surfacematerials such as powdered stone to the back side of the web of shinglematerial, which will become the back surfaces of finished shingles. Thebacking surface material prevents or helps to prevent shingles fromsticking together when bundled. Although not shown in the schematicdrawing of FIG. 1, the web may be flipped over in known ways between thegranule application station 17 and the backing material applicationstation 19 so that the backing material can be applied as a droppingcurtain to the back side of the substrate.

Cellophane strips 25 are applied from rolls 20 to the back of the web ofshingle material. These cellophane strips are positioned across the websuch that when shingles are cut from the web and stacked in bundles, thecellophane strip of each shingle will overlie the glue strips ofshingles below to prevent the glue strips from sticking shinglestogether in the bundle. The web of shingle material, still hot, thenpasses through a cooling accumulator or cooling looper 21 where thesubstrate cools and is accumulated so that manufacturing can continue inthe event of a problem upstream of the cooling accumulator 21, such asthe need to change the rolls 20 of cellophane strip material.

The web of shingle material is then cut into individual shingles at acutting station 22 and stacked into bundles 23 at a stacking station.These stacked bundles are then wrapped at a wrapping station 24 to formwrapped bundles, which may then be palletized 28 at a palletizingstation 27. A wide gamut of variations of the just described process maybe implemented. For instance, in the manufacture of layered shingles,additional steps may include cutting a top layer strip from the web ofshingle material, aligning the top layer strip over a bottom layerstrip, and bonding the layers together with an appropriate adhesive.However, FIG. 1 illustrates the typical basic sequence of events in themanufacturing of asphalt shingles.

With the forgoing in mind, it has been found that some of the typicalmanufacturing steps and the finished shingles themselves can be enhancedthrough the use of films applied to the web of shingle material. In oneparticular pertinent example, a film, usually of a polymeric material,can be applied to the back surface of the web of shingle material inplace of a back dust material. For example, instead of applying powderedmineral or glass to the back of the web of shingle material, a thin filmof polymeric material may be applied. Such a material can function aswell as or better than traditional back dusting materials, can provideadditional advantages, and can be more economical and less complicatedto apply. Films can also be applied over the head lap portions ofshingles as protective barriers or even over the exposed areas and tabsto provide additional UV protection and other advantages.

In the past, the application of films to certain portions of asphaltshingles during the manufacturing process has been suggested. U.S.patent application 2010/0005745 of Harrington, Jr., for instances,discloses a roofing shingle with a polymer film backing. A film ofpolymeric material is applied from a prefabricated roll onto the back ofa web of shingle material during the manufacturing process. It isasserted that the film alleviates the need for back dusting material,eliminates the back dusting step, and prevents shingles from stickingtogether. However, as mentioned above, application of films to a shinglesubstrate from prefabricated rolls is problematic since the film must bethicker than is necessary to provide the benefit, rolls of film must bechanged out when the rolls are empty, and sourcing, shipping, andstorage of large rolls is necessary.

FIG. 2 illustrates, in highly simplified schematic form, one embodimentof an apparatus for carrying out the methodology of the presentinvention. According to the method, polymeric material in a molten orotherwise liquefied state is extruded onto the moving surface of a webof shingle material and allowed to cure to form a film. The inventionwill be detailed within the context of extruding a film onto the backsurface of the web of shingle material as a substitute for applicationof back dusting material. It will be understood, however, that theinvention includes extrusion of films onto other surfaces and inpatterns that will position the films on any desired portions offinished shingles.

A film extrusion station 50 is located along a shingle manufacturingline 40 at a preselected location. In the example of FIG. 2, the station51 is located downstream of the saturation and filled asphalt coatingstations. Here, a web of shingle material 32 comprises a saturatedsubstrate having a filled asphalt coating on the top surface of thesubstrate. Appropriate supports such as rollers 46 support the web ofshingle material as it traverses the film extrusion station 50. A vessel52 contains a supply of molten or otherwise liquefied polymeric materialthat is maintained at a predetermined desired to temperature andviscosity. A high pressure pump 54 is in communication with the vessel52 via conduit 53 such that the pump 54 can draw liquefied polymericmaterial from the vessel. Alternatively, a polymer pellet hopper maysupply polymer pellets to an extruder, which heats and melts the pelletsas they are conveyed by internal screws along the extruder.

An extrusion die 58 is located adjacent the bottom surface of the web ofshingle material. Here it is shown below the web, but the web might justas well be inverted and the extruder located above the web. Theextrusion die 58 may be a slot die having a long slot-shaped nozzlethrough which material is ejected. Alternatively, the extrusion die 58may be any type of die capable of ejecting a stream or streams, perhapsconfigured as a thin sheet or curtain, of liquefied polymeric materialunder pressure toward the web of shingle material 32. In any case, theextrusion die 58 has its inlet port coupled to the outlet of the highpressure pump 54 through high pressure conduit 57, or, if an extruder isused, to the outlet of the extruder. The pump, when actuated, deliversliquefied polymeric material under high pressure through the conduit 57to the extrusion die 58, which ejects the polymeric material toward theweb of shingle material 32. In a preferred embodiment, the extrusion die58 comprises one or more slot dies that eject a thin curtain or curtainsof polymeric material toward the web.

The high pressure pump 54 is of a type that can be controlled to deliverpolymeric material at a predetermined pressure within a range ofpressures. A machine controller 59, which may be a computer or aprogrammable logic controller (PLC), is operatively connected to thehigh pressure pump 54 via an appropriate connection 61. The machinecontroller 59 is programmed to monitor various parameters of theproduction process and to control the pump 54 such that a predeterminedvolume-per-second of polymeric material at a predetermined pressure isdelivered to the extrusion die. The predetermined volume and pressureare calculated or otherwise selected such that a film of polymericmaterial having a predetermined thickness is deposited on the moving webof shingle material at the line speed of the web, which may be about 500feet per minute or higher.

In the illustrated embodiment, the extrusion die is configured to applya film of material to the bottom surface of the web. The film may spanthe width of the web from one side to the other, or may be applied onlyin predetermined regions. This bottom surface of the web will become theback surfaces of finished shingles and of shingle layers, such as adragon tooth layer, when shingles and layers are cut from the web ofshingle material. The extrusion die in this embodiment ejects a curtainor sheet of liquefied polymeric material toward the bottom surface ofthe web so that the material initially sticks to the saturatedsubstrate, which is still hot and partially molten. A chilled air blower59 or other chilling mechanism (such as a wet looper for example) may besituated just downstream of the extrusion head 58. The blower 59 isconfigured to direct streams of chilled air 51 toward the liquefiedpolymeric material just applied to the saturated substrate. This curesand hardens the polymeric material into a thin film 61 that is bonded tothe back surface of the saturated substrate. The web then moves on indirection 62 to other stations such as a granule application stationwhere the fill coated top surface of the web receives protective ceramiccoated granules.

In the just described embodiment, the film of polymeric material isapplied in lieu of the application of a back dusting material and inlieu of traditional protective cellophane strips. These elements andtheir stations along the manufacturing line are eliminated. Theextruded-on film performs the functions of both of these traditionalelements and, in fact, performs them better than the traditionalelements. For example, the film prevents finished shingles from stickingtogether when stacked into bundles and also prevents the glue strips ofone shingle from sticking to the back of an overlying shingle in thebundle. As an added benefit, the film is much smoother and dust freethan traditional back dusting material and forms a better surface foradhesive bonding between layers of architectural shingles and betweenshingles of adjacent courses on a roof.

Extrusion of films onto webs of shingle material according to thepresent invention provides advantages in addition to those discussedabove. For example, since it does not rely on prefabricated rolls ofpolymeric film, the application of film can continue indefinitelywithout the need to stop and change out rolls when one roll is empty.The extrusion mechanism is simpler, self-contained, and more reliablethan mechanical mechanisms for applying back dust material to a web ofshingle material. Further, the application of the film is controllablein real time simply through a command from the controller 59 to the pump54 (or extruder). The extrusion die itself can be configured andpositioned to apply film to virtually any portion of the substrate webso that the film ends up on a desired portion of the finished shingles.Film can also be applied in patterns by starting and stopping theejection of material from the extrusion die as required or providingmultiple extrusion dies.

FIG. 3 shows in lateral cross-section a simple shingle manufacturedaccording to the method described above. The shingle 81 comprises asubstrate material 82 at its core. The substrate material may be a glassmat, and may be saturated with sealing asphalt, which forms a thinwaterproof layer 83 on top of the substrate and a thin layer 84 on thebottom of the substrate 82. A layer or coating of filled asphalt 86resides atop the saturated substrate on the top portion of the shingle.Protective ceramic coated granules 89 are embedded in the filled asphalt86 in the exposed portion 87 of the shingle to provide protection fromthe elements. The headlap portion 88 of the shingle also may have someless expensive granules applied to its surface and/or may have a dustingof material to prevent sticking when shingles are stacked in bundles. Athin film 91 of a polymeric material covers the back of the shingle. Thefilm 91 is extruded onto the back of the shingle and cooled as discussedin detail above and thus is bonded to the saturated substrate. The film91 provides various advantages such as preventing sticking by replacinga traditional backing material, increasing the reliability of the bondbetween shingle layers, and rendering the shingle more flexible.

In the forgoing description, application of a polymeric film onto theback of a substrate that has been pre-saturated with asphalt has beendiscussed. It has been found, however, that an extruded film ofpolymeric material on the back surface of a shingle substrate canprovide advantages beyond elimination of a back dust and cellophanestrips. Specifically, the extrusion of a thin polymeric film onto ashingle substrate such as a glass mat can itself seal the substrateagainst moisture penetration rendering it waterproof. This can eliminatethe need to saturate the substrate with asphalt to form the seal. Thisconcept will be described with reference to FIGS. 4 and 5.

FIG. 4 shows, in greatly simplified form, a shingle manufacturingprocess that incorporates an alternate embodiment of the invention. Aroll 102 of substrate material, which may be a glass mat or an organicfelt, is paid out along a processing path in direction 103. Thesubstrate may pass over a splicing table (not shown), through a feltlooper or accumulator (not shown), and over and under various supportrollers such as roller 104. Ultimately, the web of substrate passes apolymer extrusion die 114 that, as in FIG. 2, is fed with molten polymer116 from a reservoir 107 and a pump 109 through conduit 113.Alternatively, a traditional internal screw extruder may be used to meltthe polymer 116 and deliver it to the extrusion die. Also as in FIG. 2,the pump 109 (or an extruder) is controlled by a controller 111 to ejecta sheet or curtain of molten polymeric material onto the bottom surfaceof the web of substrate material at a predetermined rate. This, inconjunction with the line speed at which the substrate material isconveyed, determines the thickness of a polymeric film deposited ontothe bottom surface of the mat of substrate material.

The film of polymeric material is substantially molten when firstapplied and must be cooled and cured. For this purpose, the substrate106 with polymer film coating 144 (FIG. 5) may pass various coolingstations, illustrated in FIG. 4 by chilled air blowers 117, and chilledrollers 118. Of course, the arrangement of these elements at the coolingstations may be far more complex than illustrated schematically in FIG.4 but such arrangements are generally known to those of skill in theart. When the polymer film coated substrate is sufficiently cooled, itis conveyed through an asphalt coating station 119 where a filledasphalt coating is applied to the upper surface of the substrate. Again,the process of applying the filled asphalt is generally known to theskilled artisan, but may include an asphalt head that pours hot asphaltonto the upper surface of the substrate and one or more doctor blades ormetering rollers 122 to meter the amount of asphalt that remains on thesubstrate. Excess asphalt removed by the doctor blade or roller may fallinto a reservoir 123 for subsequent use.

The filled asphalt coated polymer filmed substrate next passes thegranule application station 124, wherein ceramic coated granules 126 aredeposited onto the hot molten asphalt applied at station 119. Downstreamof the granule application station 124, the resulting web of shinglestock may be cooled, the granules may be pressed into the asphalt, andthe web may be cut into shingles in the traditional way before beingbundled, wrapped, and palleted for shipment.

FIG. 5 illustrates in an exaggerated thickness cross-section of ashingle material web 141 that results from the methodology of thisembodiment. The shingle web comprises a mat 142 of substrate materialthat may be a glass mat, organic felt, or other appropriate material. Ifa glass mat, the substrate material may comprise multitudes of randomlyoriented glass fibers 143 bond together with appropriate binders. Thebottom surface of the mat is covered with a film of polymeric material144 applied at the polymer application station as discussed above. Sincethe polymer is extruded in a molten form onto the substrate mat, andparticularly if the mat itself is heated before application, a strongunitary bond 146 is formed between the mat and the polymer film.

The thickness of the film can vary widely depending upon the propertiesit is intended to provide. For instance, thinner films may suffice toprovide a moisture barrier while thicker films may supply rigidity,penetration resistance, or other properties. Generally, the thickness ofthe film 144 can range from about 5 microns to about 150 microns. Toprovide a simple moisture barrier, the film can be significantly thinnerthan pre-fabricated films applied from a supply roll. A thin polymerfilm 144 between about 5 microns and about 15 microns thick has beenfound to provide a waterproof moisture barrier comparable to thatprovided by the traditional method of saturating the substrate with anasphalt sealant. The shingle stock 141 further comprises a layer offilled asphalt 147 within which ceramic coated granules 148 are embeddedin the customary manner.

Roofing shingles made from the mat 141 according to this embodimentexhibit improvements and advantages over shingles made from traditionalasphalt saturated and fill coated mat. For example, such shingles aregenerally lighter and more flexible than standard shingles, making themsuitable for use in many climates. As with the first embodiment, theneed to backdust and apply non-stick cellophane strips to the backs ofshingles is eliminated, which eliminates complex hardware from themanufacturing process and reduces manufacturing time. Significantly, thetraditional need to waterproof the shingle substrate by initiallysaturating it with liquid asphalt is eliminated as a waterproof seal isformed by the extruded polymer film. This can reduce manufacturing costsand reduce asphalt usage. The polymer film also has proven to besurprisingly slip resistant, which can be a benefit during shingleinstallation.

The invention has been described herein in terms of preferredembodiments and methodologies considered by the inventors to representthe best modes of carrying out the invention. It will be clear, however,that a wide gamut of additions, deletions, and modifications, bothsubtle and gross, may be made to the illustrated exemplary embodimentswithout departing from the spirit and scope of the invention itself. Forexample, while the molten polymer is illustrated being ejected orsprayed in sheets or curtains from below the moving substrate, it couldjust as well be applied from above and the substrate inverted prior toadditional processing steps. While not explicitly illustrated, it isbelieved to be advantageous when using a glass mat substrate to heat thesubstrate before applying a polymer film. This forms a better and moremonolithic bond between the substrate web and the polymer film appliedthereto. In fact, manufacture of the glass mat itself might well beincorporated into the overall process. In such case, a fiberglassprecursor might be passed through an oven to bond the glass fiberstogether with appropriate binders at an upstream location. The polymerfilm might then be extruded directly onto the resulting fiberglasssubstrate before it cools. These and other modifications might well bemade by one of skill in the art, all within the scope of the invention.

What is claimed is:
 1. A method of fabricating roofing shinglescomprising the steps of: (a) conveying a mat of substrate materialhaving a first and a second surface in a downstream direction; (b)ejecting a stream of molten polymeric material onto the first surface ofthe mat of substrate material as the mat is conveyed in the downstreamdirection to deposit a film of polymeric material on the first surface;(c) cooling the film of polymeric material to cure the film, bond thepolymeric material to the mat of substrate material, and form awaterproof coating on the mat of substrate material; (d) coating thesecond surface of the mat of substrate material with a bituminouscoating that is at least partially molten; (e) embedding ceramic-coatedgranules into the bituminous coating to form a protective layer; (f)cutting the resulting mat to form individual shingles; and (g) bundlingthe individual shingles for storage and shipment.
 2. A method offabricating roofing shingles as claimed in claim 1 where in step (a) themat of substrate material comprises a glass mat.
 3. A method offabricating roofing shingles as claimed in claim 1 where in step (a) themat of substrate material comprises an organic felt mat.
 4. A method offabricating roofing shingles as claimed in claim 1 wherein the firstsurface of the mat of substrate material will become the back surfacesof shingles.
 5. A method of fabricating roofing shingles as claimed inclaim 1 wherein the second surface of the mat of substrate material willbecome the top surfaces of shingles.
 6. A method of fabricating roofingshingles as claimed in claim 1 further comprising saturating the mat ofsubstrate material with a bituminous material prior to step (b).
 7. Amethod of fabricating roofing shingles as claimed in claim 1 whereinstep (c) comprises subjecting the film of polymeric material to an airstream.
 8. A method of fabricating roofing shingles as claimed in claim1 wherein step (c) comprises passing the mat of substrate material overchilled rollers.
 9. A method of fabricating roofing shingles as claimedin claim 1 wherein step (b) comprises ejecting the stream of moltenpolymeric material as a curtain.
 10. A method of fabricating roofingshingles as claimed in claim 9 wherein step (b) further comprisesforcing the molten polymeric material through a slot die toward thefirst surface of the mat of substrate material.
 11. A method offabricating roofing shingles as claimed in claim 1 further comprisingthe step of ejecting a stream of molten polymeric material onto at leasta portion of the second surface of the mat of substrate material.
 12. Amethod of fabricating roofing shingles as claimed in claim 11 furthercomprising ejecting a stream of molten polymeric material onto theportion of the second surface of the mat of substrate material that willbecome a headlap portion of shingles cut from the mat.
 13. An apparatusfor fabricating roofing shingles comprising: a processing line alongwhich a mat of substrate material having a first surface and a secondsurface is conveyed in a downstream direction; a die positioned alongthe processing line and configured to eject a stream of molten polymericmaterial onto the first surface of the mat of substrate material as themat is conveyed in the downstream direction to deposit a film ofpolymeric material on the first surface of the mat of substratematerial; a supply apparatus for supplying molten polymeric material tothe die under pressure; a cooling apparatus for cooling the film ofpolymeric material after it is ejected onto the first surface of the matof substrate material; a coater configured to apply a coating ofbituminous material in molten form to the second surface of the mat ofsubstrate material; a granule applicator for applying ceramic-coatedgranules to the coating of bituminous material, the granules becomingembedded in the bituminous coating to form a protective layer for thebituminous material when exposed to the elements; a cutting station forcutting the finished mat into individual shingles; and a packagingstation for bundling the individual shingles and packaging the bundlesfor storage and shipment.
 14. The apparatus of claim 13 wherein the diecomprises a slot die.
 15. The apparatus of claim 13 wherein the supplyapparatus comprises a source of molten polymeric material and a pump fordelivering the polymeric material from the source to the die.
 16. Theapparatus of claim 13 wherein the supply apparatus comprises anextruder.
 17. The apparatus of claim 13 wherein the cooling apparatuscomprises a chilled air blower.
 18. The apparatus of claim 13 whereinthe cooling apparatus comprises chilled rollers.
 19. In a process forfabricating roofing shingles wherein a mat of substrate material isconveyed along a processing path and material is applied to the mat tobuild up a web to be cut into individual roofing shingles, theimprovement comprising locating an extrusion die along the processingpath adjacent at least one surface of the mat of substrate material,ejecting molten polymeric material through the extrusion die onto themat to form a film of polymeric material on the at least one surface ofthe mat of substrate material, and cooling the film of polymericmaterial to bond the polymeric material to the substrate material. 20.The improvement of claim 19 wherein the at least one surface will becomethe back surfaces of shingles cut from the web.
 21. The improvement ofclaim 20 further comprising saturating the mat of substrate materialwith a bituminous material prior to forming a film of polymeric materialon the at least one surface of the mat of substrate material.